Abstract Despite global success of interventional cardiac surgery for treatment of arrhythmias, electroanatomical mapping (EAM) of the heart has significant drawbacks. The procedure is slow and prone to registration errors, largely ineffective for treating transient arrhythmias, such as ventricular tachycardia, and exhibits relatively poor spatial resolution. With only a 50% success rate for first-time interventions, these limitations contribute to multiple erroneous ablations, repeat procedures, and increased complications for the patient. This Phase 1 SBIR proposes to develop and validate 4D Acoustoelectric Cardiac Imaging (ACI) technology for mapping electrical current in the in vivo pig heart. ACI is a patented technology that offers real-time capability and superior spatial resolution (<2 mm) for rapid localization of arrhythmias during ablation therapy. Our preliminary studies suggest that ACI would offer the following benefits over conventional EAM: 1) 4D real-time imaging of current densities in the heart; 2) high spatial resolution determined by the US focus (0.2 - 2 mm); 3) accurate localization of both sustained and transient arrhythmias; 4) fusion of current densities (ACI) with cardiac anatomy and motion (pulse echo US). The primary goal of the Phase 1 SBIR is to demonstrate and validate ACI for in vivo mapping of the electrocardiogram and cardiac activation wave in the live pig. The project partners ElectroSonix LLC with The University of Arizona to enhance the ACI platform and assess performance for in vivo mapping of electrical current in a wild type pig model. Our ultimate vision is to develop a mobile or even portable platform based on proprietary ACI technology (i.e., hardware, signal processing, data analysis and integration) for fast, real-time mapping of arrhythmias that is far superior to state-of-the-art electrical cardiac mapping techniques. A successful demonstration in the pig heart (Phase 1) would lead to an expanded Phase 2 project directly comparing ACI with a commercial EAM system (e.g., GE CARTO) for image-guided ablation during treatment of arrhythmias. The overarching goal is to improve the success rate of resynchronization therapy and reduce chances of complication by limiting the number of unnecessary ablations and repeat procedures. This would effectively reduce the chances for medical errors and improve the quality of life in patients who receive treatment. The value from this SBIR will be the first step towards commercializing a fully integrated ACI medical device realization.